The present invention relates generally to devices for spacing and damping conductors of overhead electric lines, and particularly to an extremely lightweight, low-cost, damping spacer in which substantially all metallic components thereof are made from wrought materials.
In a previous patent, U.S. Pat. No. 4,178,467 (issued to R. G. Hawkins, one of the present applicants), there is disclosed a lightweight rigid spacer device wherein spacing is provided by use of a thin-wall, hollow channel member, the channel typically being an extruded product. A lightweight, resilient strap means is also used to connect the spacer bar to the conductor. While the spacer works very well for its intended purpose, it does not provide damping against wind-induced vibration occurring in the conductors. Devices providing such protection, in addition to spacing, are typically referred to in the trade as spacer dampers or damping spacers.
Heretofore, damping spacers typically have been rather large and heavy, generally as a result of using rather heavy cast parts. For example, U.S. Pat. No. 3,885,086, to Houston et al, discloses a damping spacer assembly having a cast housing and cast conductor clamp arms. Also, U.S. Pat. No. 3,609,209, to Houston et al, discloses a damping spacer having cast conductor clamp arms. Similarly, U.S. Pat. No. 4,188,502, to Gagne, discloses a damping spacer having a metallic frame made of cast aluminum. In addition, while U.S. Pat. No. 3,748,370, to Dalia, does not mention how the components of the damping spacer described therein are formed, it appears from the drawings that the clamp arms and frame could not be feasibly made by any process other than casting.
Cast products inherently suffer from certain inadequacies not present in wrought products, particularly wrought extruded products. For instance, cast products lack the strength of wrought products. To compensate for this, cast products use more metal than wrought products, thereby adding weight and expense to the final cast product. Furthermore, even with more metal, cast products are invariably less reliable than wrought products. Excessive porosity, blow holes and dimensional inaccuracy act and interact, particularly in the case of sand castings, to lessen reliability. In addition, the surface of a cast product is invariably much rougher than a wrought product's unless, of course, the cast product is machined. However, machining, which adds time and expense, is not desirable. Machining is also undesirable in that the stresses added to those areas machined have the overall effect of weakening the part produced.
Accordingly, it would be desirable if a damping spacer could be produced having wrought metal components. Since less metal would be required, savings in cost would result. Even more importantly, structural integrity and operational reliability would be dramatically improved.